FateMass Alter
by Canis Lupus 54
Summary: Angra Mainyu gets bored and summons Servants from other universes, but probably not the ones you're expecting.
1. Chapter 1

AN: This has bounced back and forth between being an original work and a fanfic. The only reason it's still a fanfic is because I wanted to use Saber and Archer. I hope you enjoy it.

Angra Mainyu was bored. The Fifth Holy Grail War was coming up and the Servants set up to be summoned were just so… standard. Archer was an anomaly, sure, but he was just one Servant. Plus he was after revenge… against himself. Okay, so Archer was pretty badass, but still. There had to be some way to spice things up. Why not pull in some random bystanders? Yeah, and have more than seven Servants too!

Wait, that had been done. Alternative Servants? Done. Fictional character Servants? Seen it. But what about Servants from other universes that weren't fictional characters. In the infinite multiverse, there was an infinite pool of Heroic Spirits to choose from. And he could still have more than seven of them.

His decision made, Angra Mainyu set about selecting the Servants.


	2. Chapter 2

Kazuto sighed and watched his breath float up in the cold air. He didn't know why he was sighing, it just felt appropriate. He probably should've been at home. Or at the Paranormal Investigation Club. Somehow they just weren't the same, though. The teachers kept talking about how being in a club was important, but it just felt hollow to him.

He sighed again and opened the book he was carrying. Magic. That was what he wanted. Not the wild goose chases of the Paranormal Investigation Club, but something real, tangible. He had told the club president, Kasumi Adashino as much when she last asked about his frequent absences from the club's meetings.

"This is your only warning," the message echoed through his mind.

Flipping through the book, something caught his eye. A summoning of some sort. He heard that a serial killer ten years ago had been killed after attempting to summon a demon or something like that.

Kazuto sighed again. Might as well go out in style. With a grim smirk, he headed into the woods surrounding Fuyuki City. He drew the circle and started the incantation.

"Shut (fill). Shut (fill). Shut (fill). Shut (fill). Shut (fill).  
Repeat every five times.  
Simply, shatter once filled.  
――――I announce.  
Your self is under me, my fate(doom) is in your sword.  
In accordance with the approach of the Holy Grail, if you abide by this feeling, this reason, then answer.  
Here is my oath. I am the one who becomes all the good of the world of the dead, I am the one who lays out all the evil of the world of the dead.  
You, seven heavens clad in three words of power, arrive from the ring of deterrence, O keeper of the balance ―――！"

He felt a burning on his hand and looked down to see a strange red marking there. The circle started to glow and in a flash of light, a girl about his age appeared. Kazuto stumbled backwards in surprise and fell over.

Standing at roughly one hundred fifty-five centimeters, the girl was clothed in a short black dress, a black cape, and a black witch's hat. She had long blue hair and red eyes. She looked around briefly, then turned to Kazuto.

Then she smiled. "Hi, hi! Servant Caster accepting your summons! Are you my Master?"

"I, um, summoned you," Kazuto said, holding up his hand to show the markings.

"The contract is complete, then. You seem a little confused. Are you okay?"

"Aren't you going to eat me, or something?"

The girl scowled and put her hands on her hips."No! Why do people always think I'm going to do that?"

"It's just, I thought I summoned a demon."

"Oh, we should get to the nearest Catholic church, the priest should be able to get you up to speed."

"Right…"

Kazuto didn't actually know where the nearest Catholic church was off the top of his head, so after some googling, the two set off for the Kotomine Church. Caster elected to stand guard outside, while Kazuto went inside. It was surprisingly dark, almost ominous, inside.

"Um, excuse me," he said into the darkness, "This girl names Caster appeared in my room and this marking appeared on my hand."

"I can explain everything," said the priest, seemingly appearing from nowhere. "Come, child."

Kazuto followed the priest into an office-looking room, where the priest launched into a lengthy speech.

"You have been entered into a sort of game known as the Holy Grail War," he said. "In this War, seven humans known as Masters will command seven legendary heroes brought to life. We call these heroes Servants. They go by the name of their classes to protect their identity."

"Because if you know their identity, you know their strengths and weaknesses?"

"Exactly so. The seven classes are Saber, Archer, Lancer, Rider, Caster, Berserker, and Assassin. I trust the names are self-explanatory. These Servants are capable of feats far beyond an ordinary human, or even an ordinary magus. As such, Master's usually fight each other, while setting their Servants against one another. Your Servant, Caster, is generally considered weak in direct combat so you may wish to avoid conflict. If your Servant is defeated try to get here. The Church will protect you."

"What exactly am I fighting for?"

"The Holy Grail is an artifact that can grant wishes. Any wish your heart desires."

Kazuto sighed. "Guess I can't just let anyone get it, then. Thanks for the info."

The priest held retrieved a book from a shelf and handed it to Kazuto. "Here, take this book. It will update with information on the Servants you encounter."

"Thanks, I'll be going now."

Kazuto turned and left the church. Honestly, the atmosphere and the priest were both a little creepy. As he walked out of the church, Caster shouted to him.

"Master, look out!"

Kazuto noticed something rushing at him out of the corner of his eye and stumbled backwards. Something knocked him over and suddenly he couldn't see.


	3. Chapter 3

Kazuto panicked. He was the ground, couldn't see, and he couldn't breath. What was going on? Then, light and air returned to him and he realized Caster had knocked him down and inadvertently covered his face with her bosom. He blushed luminously as he realized that. Caster stood up and moved to stand in front of him with her back to him.

"I'll take care of your carnal desires late, Master!" she told him. "For now, I have a battle to win! Any orders?"

Kazuto looked past Caster to see a pale skinned woman with black hair done up in a bun standing opposite her. The pale skinned woman was clothed in a bikini bottom, and some sort of top that was both low-cut and split near the stomach, making it very exposing. She was holding a black spear in one hand. Presumably, she was Lancer.

"What is she wearing?" Kazuto exclaimed, sitting up. "Um, kill her!"

"Yes, Master!" Caster said with a salute. Then her words turned into an indistinct blur as she traced a circle with her finger in the air. A fireball came out of the circle and launched at the other woman. Lancer backflipped away. Caster said something else and the ground where Lancer was going to land crumbled away. In an instant, Caster was right in front of Lancer, kneeing the pale woman in the stomach, then kicking her away.

Lancer recovered and landed on her feet, then launched at Caster, stabbing with her spear. Caster didn't dodge, opting instead to grab the spear by its shaft and heave upwards, flipping Lancer over Caster's head and slamming Lancer down into the ground head first. Caster then released the spear and ran back around Lancer, making sure Caster was between Kazuto and Lancer.

She started talking at high speed again, raising her hands and making a clapping motion. Two walls of rock rose up on either side of Lancer and started closing in. Lancer stood, used her spear to keep the rock walls apart and flipped out of the trap, taking her spear with her. She landed and launched towards Caster once again, stabbing with her spear.

Caster materialized a plain wooden staff and parried the spear blow, then spoke again and a massive explosion came from the staff's head, sending both her and Lancer flying backwards. Caster landed gracefully by Kazuto, while Lancer landed on her back and tumbled some before sliding to a stop. She then stood and regarded the two with a slight scowl.

Lancer prepared for another charge, then stopped and cocked her head, as if listening to someone.

"Whatever," she said, before running off into the night.

Kazuto realized he hadn't stood up yet and got up.

"We should get home," he said.

Caster nodded. "That's right! Let's get going then!"

The two walked back to Kazuto's home. Kazuto gulped and hesitated before opening the door. How was he going to explain Caster to his parents? Well, he had to face this sooner or later. He opened the door and stepped in, Caster following behind him.

"I'm home," he said simply.

"Welcome home!" came his mother's voice from the kitchen. He walked over there and found both his mother and father waiting for him. They both gave him and Caster a questioning look. He could practically see the question on their lips. Then, Caster pointed at them and said a couple words of her gibberish. His parents' eyes glazed over for a second, then they returned to normal.

"Kazuto, Caster, dinner's ready," his mother said.

"Yummy, let's eat!" Caster replied.

They ate, then Caster and Kazuto retired to the latter's room.

"What did you do?" he asked Caster.

"I just made them think me being here is normal. Don't worry, I used Mind Alter, even though I prefer Mind Break, personally," Caster replied, then she spoke in some of her gibberish while pointing at the walls, ceiling and floor. She shrugged off her cape and put her hat on the desk in the room.

"Oh… good," Kazuto said as Caster started getting out of her dress. "What are you doing?"

"I promised I'd satisfy your carnal desires, remember?"

"You don't need to! What about my parents?"

"They think we do this every night."

"What? How? Why?"

"Okay, let's get started!"

...

"So, another unknown hero appears," Kotomine said.

"Yes, these fake Heroic Spirits are quite irritating. At this rate who even knows if any real heroes will show up?" Gilgamesh replied. Suddenly, a spear was at his back.

"Don't call us fake," Lancer's voice said calmly.

"Indeed, after that display I think they've earned their title. Or Caster has, at least," Kotomine cut in.

Gilgamesh shrugged. "We shall see."


End file.
